This is one of the first things I work on with my perinatal clients, as it’s often overlooked. Many doctors don’t specify what kinds of nutrients are necessary to supplement, which forms of these nutrients are most absorbable, or the recommended dosage of each.
Supplements are unregulated, and can vary wildly in terms of their content, so it’s important to ensure you’re getting high-quality, bioavailable nutrients so that you’re not wasting your money.
In addition, many of my clients get incorrect information about what they need during this unique time in their lives. For example, contrary to popular belief, the RDA for calcium does not increase during pregnancy, but stays constant at 1,000mg for all women aged 19-30, regardless of whether they are pregnant or lactating.
It’s also important to note that the Recommended Daily Allowance (RDA) is not necessarily what you think it is. The Recommended Daily Allowance is defined as “the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people.”
What this means is that the RDA isn’t necessarily what’s recommended for optimal health; it’s more like the minimum recommended for your body to function properly. A separate chart, Upper Tolerable Limits (UL), notes the “maximum daily intake unlikely to cause adverse health effects.”
Of course, theoretically, we should be able to get all our nutrition from our food. And if you’re eating lots of clean, whole foods like organic vegetables and pastured meats, a supplement may feel redundant. However, I still recommend that all my perinatal clients take one (see why here).
That said, the healthier you eat, the more flexibility you may have in terms of the dosage of your supplement (perhaps you may feel safe taking half the recommended dose).
With that in mind, here is my guide to ingredients and dosages, as well as a recommendation for my favorite prenatal supplement (and where to buy it).
B-complex
Perhaps the single most important nutrient for moms-to-be, folate requirements nearly double when you become pregnant1. Supplementation pre-conception prevents spina bifida2 and, potentially, autism3. For this reason, it’s important to start taking a supplement well before you get pregnant.
However, there are some very important distinctions between the natural form of Vitamin B9 (folate) and the synthetic form that’s commonly found in fortified foods & supplements (folic acid). Up to 50% of the population has a genetic mutation preventing them from metabolizing folic acid. In addition, folic acid has been associated with cancer, maternal infection, and abnormally slow fetal heart rate (4). Therefore, you must look for the L-5-MTHF form.
(The USDA alludes to this differentiation in their table of Tolerable Upper Intake Levels. A note at the bottom of the table explains that the UL for folate only applies to synthetic forms “obtained from supplements, fortified foods, or a combination of the two.”)
If you’d like to get more folate from your food, you can add more green leafy vegetables, black-eyed peas, brewer’s yeast, liver, and beans to your diet.
Supplementing with folate can obscure a B12 deficiency, so if you’re going to take folate, I highly recommend supplementing with B12 as well. Look for the methylcobalamin form, which is more easily absorbed and used than the cyanocobalamin form. In foods, Vitamin B12 is only found in animal products.
B-vitamins work in concert with one another, and the Daily Recommended Intakes for almost all of them rise during pregnancy, so the best option is to choose a multivitamin that provides all of them together.
In terms of dosages, B vitamins are water soluble, which means that they flow easily throughout the body. Most B vitamins do not have an upper limit due to lack of evidence of adverse health effects.
Insufficient B vitamins may be associated with morning sickness, so supplementing may help alleviate symptoms.
B-vitamin food sources include nutritional yeast, yogurt, peanuts, and organ meats.
Magnesium
The Recommended Daily Allowance for magnesium increases to 350mg per day when you’re pregnant, depending on your age (if you’re over 30, you require 360mg). Look for a chelated form, such as magnesium citrate or glycinate.
Magnesium helps build & repair tissues and is necessary for protein formation & cellular replication. Deficiency is associated with preeclampsia and poor fetal growth. Excess calcium intake can also reduce the absorption of magnesium, since they are mineral partners that need to be balanced1.
To increase magnesium in your diet, eat pumpkin seeds, sea vegetables, almonds, cashews, brewer’s yeast, and leafy greens.
Zinc
Zinc is an antioxidant mineral and is important for protein & DNA synthesis. Deficiency is associated with miscarriage and low birth weight.
Food sources include oysters, steak, and pumpkin seeds.
The RDA for Zn increases from 8mg to 11mg when you’re pregnant. In supplements, look for chelated zinc, such as zinc glycinate, zinc picolinate, and zinc citrate.
Zinc’s mineral partner is copper, so they must be in balance. Therefore, it is often recommended to take supplemental copper (at a ratio of 1 to 10) if you take supplemental zinc4. The RDA for copper increases to 1000mcg/day when you’re pregnant, so that's another good reason to look for copper in your prenatal multi.
Selenium
Selenium is a powerful antioxidant that can be found naturally in Brazil nuts. The RDA increases from 55mcg to 60mcg during pregnancy.
When it comes to minerals, chelated forms are often the best, so look for something ending in -ate, such as selenium glycinate or aspartate.
Chromium:
The Adequate Intake (AI) for chromium rises from 25 to 30 mcg/day when you’re pregnant. While the RDAs for some other trace minerals also increase during pregnancy (like molybdenum and manganese), chromium is the only one that you may not be able to get sufficiently from your diet. Therefore, selecting a multivitamin that includes chromium is a good idea.
Vitamin A
Vitamin A is tricky. Vitamin A deficiency can cause maternal death5, but excessive amounts are not easily excreted and can cause birth defects6. Therefore, getting just the right amount is crucial.
Whole foods are by far the best way to get your daily requirements of Vitamin A, as it’s less likely that you will consume toxic levels of Vitamin A through your diet. In addition, the natural forms of Vitamin A found in foods are more likely to be safe than synthetic versions found in some supplements.
Carotenoids, the plant-based precursors to Vitamin A, are water soluble and do not cause Vitamin A toxicity. For this reason, when it comes to your supplement, mixed carotenoids are the best choice to avoid toxicity. The RDA for Vitamin A rises from 700 to 770 mcg/day when you’re pregnant.
Beta carotene, the best known carotenoid, is found in orange plant foods like sweet potatoes and carrots, as well as dark green leafy vegetables like spinach and lettuce.
However, carotenoids can be problematic, as not all beta carotene is converted into Vitamin A7. In addition, it appears that some people aren’t good at converting any beta carotene into Vitamin A8. Mixed carotenoids are a better choice, but they are still not as bioavailable as preformed Vitamin A, because they require conversion.
Preformed Vitamin A is found in animal foods like liver, fish oils, milk, eggs, and butter. Adding these foods to your diet in moderation - along with your orange veggies and a supplement containing mixed carotenoids - is what I recommend in order to reach a healthy Vitamin A intake.
Vitamin C
The RDA for Vitamin C increases to 85mg/day when you’re pregnant. Vitamin C is another great antioxidant, and it’s water soluble so toxic buildup is unlikely. That said, excessive amounts of Vitamin C (> 2,000mg/day) “may contribute to the formation of kidney stones, as well as cause severe diarrhea, nausea, and gastritis”9.
While most of us think of citrus fruits when we think of Vitamin C food sources, bell peppers, broccoli, and brussels sprouts have even higher concentrations of Vitamin C.
Omega-3 fatty acids
There is no recommended daily amount for these nutrients, but studies show that they are crucial for baby’s health. Most experts recommend intake of 400-650mg DHA and 650-1200mg EPA11. You can get this through eating fish, or you can take a purified supplement like OmegaGenics or OmegAvail, both available in my store.
A word about iron
Iron requirements rise from 18mg to 27mg per day during pregnancy, as it’s required for the production of red blood cells and DNA. Even slight iron deficiency can lead to learning disabilities in your developing child.
However, iron is not easily excreted, and can contribute to free radical activity. For this reason, I don’t recommend supplementing with iron unless your doctor deems it medically necessary. Instead, try to get heme iron (the most efficiently absorbed type) from animal food sources like clams, steak, shrimp, turkey, and chicken. Lentils are a good non-heme iron source for vegetarians.
A word about iodine
Iodine deficiency used to be a problem in the US, and was largely rectified by iodizing salt. Nowadays, supplementation isn’t usually necessary, and due to complexities surrounding the effects of iodine intake, it also usually isn’t recommended.
That said, when you’re pregnant, your RDA for iodine rises from 150 to 220mcg/day, so you do need to be aware of your intake.
In addition to iodized salt, the ocean is an excellent source of iodine, so sea vegetables and seafoods are a great way to get iodine through your diet. Dairy products are also a good way to get sufficient iodine through your diet.
A word about Vitamin D
The RDA for Vitamin D doesn’t increase during pregnancy, but since deficiency is common, it’s often included in multivitamins. Look for the cholecalciferol form (D3), as D2 isn’t nearly as absorbable or beneficial10.
A word about Vitamin E
Your need for Vitamin E doesn’t increase when you’re pregnant, but most multivitamins include it in some form nonetheless. The best form is mixed tocopherols, although I rarely see that in supplements.
Murray, M., Pizzorno, J., & Pizzorno, L. (2005). The Encyclopedia of Healing Foods. New York: Atria.
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Hudson, T. (2008). Women’s Encyclopedia of Natural Medicine. McGraw Hill: New York.
